Remote-control system for radio receivers and the like



March 10, 1953 R. L HARVEY REMOTE-CONTROL SYSTEM FOR RADIO REJEIVERS AND THE LIKE Filed Aug. 31. 1949 2 SHEETS--SHEET 1 ATTORNEY 5 March l0, 1953 R. l.. HARVEY 2,631,280

REMOTE-CONTROL SYSTEM FOR RADIO RECEIVERS AND THE LIKE 2 SHEETS-SHEET 2 Filed Aug. 5l, 1949 ATTORNEY Patented Mar. 10, 1953 `UNITED STATES E FICE REMOTE-CONTROL SYSTEM FOR RADIO RECEIVERS AND THELIKE of Delaware Application August 31, 1949, Serial No. 113,305

1 Claim. 1

This `invention relates to remote control sys'- 'tems, particularly to the wireless type of remote controlsystem for controlling the Vtuning operation of 'distant apparatus such as radio receivers or'the like.

"The problem of remotely controlling apparatus with Aa iiexible type of control unit such as one based on a wireless, that is a radio type, linkage frorna remote control unit to the apparatus, has previously been met by incorporating a complete radio transmitter in the remote control unit and connecting the lapparatus to be controlled to an 'auidliary radio receiver control assembly actu- 'atedby the transmitter. Such asystem is shown Afor'exannple in U.S. Patent No. 2,297,618, granted September 29, 1942, to Grimes et al.

The'operation of aremote control unit including atransmitter is subject to several diiculties however. rlChe transmitter must have a sour-ce of power 'and this is supplied either' through connecting wires from the commercial power lines, or by means lof self-contained batteries. External Aconnecting wires are quite cumbersome to handle land greatly reduce the versatility of the 'system as Well as Vits usefulness. Self-:contained batteries, on the other hand,v have a limited life 'even When "the 'control unit is 'not "used, vand re- `cuire"periodicservicing o the unit, as Well 'as '.th'e `provision of 'spe-cial construction features -to permit `ready servicing.

Y Further difficulties with batteriesare 'thatthey 'are relatively-expensive, under certain conditions suchas high 'ambient temperatures they become discharged quite `rapidly even on open circuit, and they require the taking `of special precautions rto prevent discharged batteries 'from damaging the' unit by reason of the escape oi'battery chemica-ls.

-Another Adisadvantage of the "transmitter `type of remote control Vunit is that Vit necessarily includes relatively fragile components such as va'cuum tubes that can be easily broken or put out of commission by rough handling.

It is accordingly anobjectof thepresent-inven- "tion to provide'an improved wireless typeof` vre- L'mote control* 'system' yin which a "remote ucontrol `unit doesnot require`v batteries or a special Vpower suppl-y connection.

A iiurther Aobj ect l.of vthe invention isV the 'provisioncf an `improved remote control system Vand remote control unit in whichno delicate components r'such as vacuum tubes are present in lthe unit.

Prior 'remotelcontrol systems, such as the one shown in the above-identinedpatena in order to provide selectable types of remote control operations i. e. to change the signal output intensity as well as to change the tuning of a radio rec-eiver, have resorted to the use of interacting controls that have to be `simultaneously actuated tosuitably vary the remote control signals. This introduces some `awkwardness in the manipulation of the controls and necessitates some degree of manual dexterity and attention.

An additional object of the present invention accordingly is the provision of an improved remote -control unit in which no control elements `have to be simultaneously manipulated, and the control elements are actuated one at a time.

Still further objects of the present invention include the provision of an improved radio wave operated remote control system in which interference from undesired radio waves is substantially impossible even though the undesired Waves are of substantially the same frequency as the control Waves.

The above as well as other objects of the inven- Vtion will be more readily understood from the following description of exemplicaticns thereof, reference being had to the accompanying drawings wherein:

Figure Y1 is a block diagram `illustrating some of the general principles of a remote controlesystem embodying the present invention;

Figure 2 is asimilar block diagram of a diierent form of remote control system according to the invention;

lFigure 3 is a diagrammaticshowing of animproved remote control unit exemplifying one phase of the inventiony for use with a distant `apparatus to be controlled; and

Figure 4 is a schematc'illustration, with parts in block diagram form, of one form of control Aassembly incorporating the invention that coopcrates with' a remote unit such as that of Figure 3.

In the remote control system of the invention, `a remotecontrol unit has a radio wave reflecting component together with a control element for changing the reection characteristics of the component. An auxiliary control transmitter and receiver are connected tothe apparatus to be `controlled and provide radio `waves for reflection by the remote unit as well as sensing elements that respond to changes in the wave reflection to `effect control operations on the apparatus.

The sensing elements are connected to compare the waves that are transmitted with those that are reflected so that rene-ation changes are readily detected. Frequency modulation of the tra-nsvmitted'vvvaves will so distinguish them from other .control assembly including the controller .trolling the apparatus I0.

3 ambient waves of substantially the same frequency that there will be very little likelihood that these other waves will interfere with the Wave comparison.

The remote control unit of the invention avoids the use of delicate circuit components by having a reflection-changing arrangement mechanically pulsed or Vibrated.' A pulser and vibrator, or different vibrators are operated separately or in sequence to provide different kinds of reflection signals from which the sensing unit derives different types of control operations.

Figure 1 of the drawings shows an embodiment of the invention in which an apparatus I that is to be remotely controlled is connected to a controller l2 actuated by waves generated ata high frequency generator I4. The generated waves are transmitted by a radiator shown as a dipole antenna I6, reflected by a remote control unit I8 and received at a collector 20, shown as another dipole antenna.

A comparing circuit represented by block 22 is supplied with the waves received at collector 20 and also receives some waves directly from the generator I4, as indicated by the leads 24. Inasmuch as the reiiected waves and the directly supplied waves are carried in different paths, they will have different characteristics. Thus unless the paths are of exactly the same length electrically, the two waves will be differently phased, the comparator 22 being arranged to detect the phase difference.

Where frequency modulated Waves are supplied by generator I4, the phase difference will be accompanied by a difference in frequency, so that the comparator may simply be a frequency comparing device such as a heterodyne stage having an output or beat frequency circuit connected to selectively receive those waves corresponding in frequency to the frequency change undergone by the generated waves during the .phase separation interval of the two paths.

The comparator 22 supplies comparison-indieating waves to a senser 28 that forms part of a |2. Here variations in the reected waves are responded to and control signals derived for con- Thus by pulsing the reflection characteristics of the remote control unit I8, the comparator 22 will supply output waves correspondingly pulsed or modulated, and the senser 26 may merely be a detector stage connected to demodulate the pulses and supply the demodulated pulses to the controller I2. Power amplification may be included in the senser 26, the controller I2 or in both of these sections to assist in the control operation by raising the intensity of the control pulses to the level at which the desired controls are readily actuated.

In Figure 1, the remote control unit I3 includes a ,reflecting structure shown as a dipole antenna 28, connected to an antenna circuit changer 30. This circuit changer is connected to vary the reflection characteristics of the antenna 28 by simply changing the circuit to which it is connected. As one type of suitable construction the changer 30 is nothing more than two antenna leads and a shorting switch connected to directly short the leads as desired. By actuating the shorting operation according to a predetermined code or sequence, different kinds of control functions can be produced.

Toimprove the phase separation between the reected waves and the waves directly carried by circuit 24, a delay network can be included to delay the Waves passed either through the circuit 24 or the transmission and reflection path. This is especially advantageous where the remote unit 48 is separated from the apparatus I0 by relatively small distances such as those available inhomes or auditoriums. With such small distances the time required for waves to make the round trip to the remote lunit and back to the comparator 22 is so short as to yield a phase displacement difficult to detect and less than can be readily supplied by a delay network. By increasing the phase separation, a greater portion of a frequency modulation swing can be made available for comparison, thereby simplifying the comparison circuits as well as the wave generation.

The particular form of delay network used is not a part of the present invention. Any convenient arrangement can be used, such as the one described in Principles of Radio by the members of the staff of the Radar School, Massachusetts Institute of Technology, second edition. published 1946 by McGraw Hill Book Company, Ine., New York, N. Y. pages 2-98. Another convenient type of delay network is one that depends on the inductive coupling of circuits and makes use of the degree phase lag accompanying the inductive transfer of waves.

Where the delay is applied to the directly supplied waves passing through circuit 24, the antenna-s I6, 20 should be so disposed that there is very little energy transfer directly between them. This can be arranged by orienting them till a null'or minimum wave pickup appears at antenna 2|) with the generator I4 in operation, or by placing between the antennas a shield that prevents direct transfer of waves but permits waves to travel between the individual antennas and the remote control unit I8.

Although separate transmitting and receiving antennas I6, 20 are shown in Figure 1, their functions can be combined in a single antenna. Figure 2 shows such an embodiment of the invention. Here a frequency modulated generator I I4 supplies the Waves to be transmitted, through a delay network I I1 to an antenna I I6. Radiated Waves are reected from a remote control unit ||8 including an antenna |28, antenna circuit |29, and a set of individual circuit changers |3I,

|32, and |33. The reflected waves ||8 are re'- ceived by antenna IIS. On the generator side of the delay network ||'I, a direct path |24 is provided from the generator I|4 to a sensei` |26 connected to respond to changes in Ithe circuit |29 of the remote control unit IIB. In this way the reflected waves are given a further delay through the same delay network II'I through which theyV Were delayed in the transmission.

In the form of the invention shown in Figure 2, each of thev circuit changers |3I, |32, |33 is arranged to provide distinguishable effectsV on the reflection characteristics of the unit for controlling a signal receiver ||0. As one example of distinguishable controls, the changers are adjusted to periodically short out the antenna circuit |29 at different predetermined frequencies or sequences. Each changer may be used for a diiferent control purpose such as controlling the ,energizatiom tuning and output intensity ofthe 'The controlling actions in 'the construction of Figure 2 may be oi the typesuch as are explained in detail in the above-identified Grimes et al. patent.

Figure 3 shows the essential details of one type of `r'ernote control unit iexemplifying the invention. An antenna 228 has a pair of leads 234 connected in parallel to a pulseetype snorting switch 236 and, through a sequence vcontrol switch 238 to Va vibrating-type shorting switch 240. Connected to operate the pulse-type switch 236 is a. coded pulsing or dialing apparatus 250 similar to that used with conventional dial type telephones. The vibrating type switch 240 lis operated by a plucking or striking mechanism 260 'similar to conventional piano movements.

The pulsing mechanism shown at 268 includes a disc 25| pivotally mounted for rotation around its center, and having a plurality of fselector openings 252 distributed circularly around it. The individual openings are identified by the letters Ato J and are of a size that easily receive the finger tip of a remote control operator. A xed stop bar 253 is placed in the rotatory path of: the nger that is engaged in an opening 252.

The disc 25| is biased in a, counterclockwise direction as by the coil spring 249 and normally held. in ready position as by the engagement of an arm 255 carried by the disc with a fixed stop pin 254.` The disc is lfree to turn in the clockwise direction however. A damper mechanism 256 shown as including 'a step-up gear train 248 and an air vane governor 241, is connected to the disc to make its counterclockwise rotation by the spring 249 more uniform, and, if desired, more limited in speed.

A cam 246, rotates with the dial disci 25| and cooperates with a 'cam follower shown as a lever 251 pivoted at 258. A nose portion 245 of the lever 251 is held against the cam 246 as by the centering spring 244. A pulse pin 243 carried by the lever 251 is engaged by a movable blade 231 of v.switch 236, normally biased away vfrom a fixed contact 235 of the switch. The cam 246 has a number of cam lobes 242 positioned to vcorrespond with the individual finger openings 252 which may be identied by suitable indicia.

To operate the pulse or dial mechanism, it is only necessary to place the inger in a selected finger opening, then rotate the dial around in clockwise direction with the finger in the opening till the nger engages the stop bar 253, and then withdraw the finger. The clockwise rotation of the cam lobes 242 moves the follower nose 245 downwardly in an intermittent manner, tilting the'pulse pin 243 upwardly away from the switch blade 231. Switch 236 accordingly remains open. Upon release of the dial disc 25|., it is carried back in counterclockwise direction by spring 249 to 'the rest position shown, but this time the 'follower nose 245 is intermittently moved upwardly by the successive cam lobes 242, causing the pulse pin 243 to repeatedly bring movable switch blade 231 against the cooperating contact 235. A succession of pulsed short-circuiting of antenna leads 234 is thereby produced.

The 'pluckng or striking Amechanism 260 .is of the type shown in U. S. Patent No. 2,220,088 girantedfNovember 5, 1940., to T. L. Dewey. It includes aratchet wheel pivoted to an L-shaped control lever 263 at 265, the lever itself being pivoted at 261 and carrying an operating button or head 269. The lever 263 is biased in clock` wise direction against `a .stop member 21| by spring .213, :and in 'this position, 5a 'vibratable blade 4242 of switch 240 has its free end 244 gengaged between adjacent teeth 246 of the ratchet wheel. A spring blade 215 v`i'lx'ed at 211 also has its free end 219 engaged between other teeth y246. A stop 28| prevents the spring blade 215 from moving away from its operative range of positions.

As is more completely explained -in the Dowey patent, ldepressing the head or button 268 moves the `ratchet wheel away from switch arm 242 around pivot 261 and also rotates the wheel around lits own pivot 265 causing a tooth 246 to pluck the arm 242 and set it into vibration. A xed contact 243 cooperates with the vibrating arm 242 to cause periodic closing of switch 2-40 at a relativelyV high/'frequency so longas the armV is vibrating. Upon release of the button 269I the lever 263 is-carried back against stop 21| bringing the ratchet wheel 26| against the blade 242, arresting the vibrations and cooking the mechanism for the next operation.

The relatively slow pulses produced at switch 236 are readily distinguished from the rapid closing. of switch 240 which may have a repetition frequency 5 or more times as high. For simplifying the operation the snorting switches 236, 240 are arranged for vpreventing simultaneous action. Arm 255 of the dial mechanism coacts either the normally open switch 238 and functions to close this switch only when the dial is in its normal rest position shown. The switch 238 is accordingly open at all times during the dialing, thereby disconnecting vibrating switch 240 from atleast one `of the leads 234.

To operate the controls of Figure 3, the dial mechanism can be manipulated for one type of control action, such as the tuning shown in the Grimes et a1. patent, or the vibrating mechanism operated for a different type of control action. Suitable response mechanism such as that shown in block form in Figure 2, is provided to distinguish the control signals. More than Vone vibrating mechanism can be used to provide control signals of diferent vibratory frequencies.

Figure 4 shows the essential details of a control assembly that can be connected with a radio signal receiver to operate it with a remote control unit of the type shown in Figure 3. A frequency modulated wave generator 3|4 of any convenient type, supplies modulated high frequency waves to a heterodyne circuit 322 which may be nothing more than a crystal mixing stage. A reflectionreceiving antenna 320 supplies to the heterodyne circuit 322 waves reflected by the remote unit. The beat frequency output waves of the circuit 322 are amplified by amplifier 323 and changes in reiiection are detected by detector 326 and supplied as pulses of electric current to the winding of a relay 30| having two sets of normally open contacts 302, 303.

The energization and deenergization of relay 391 controls the operation of a positioning tun-ing control member shown schematically as a reversible electric motor 305 having separate rotation 'direction controlling windings 306, 301 and auxiliary split commutator segments 308, 309. Relay 30| also controls the operation of an output in tensity or volume control electric motor, the rotation direction control windings of which are shown at 310 and 312.

The operation of these motors is effected in the construction of Figure 4 in a manner similar to that shown in U. S. Patent No. 2,241,157., .granted May 6, 1941, to W. T. Powell. A progressively moving or stepping switch 380 of the type 7 .described in U.S. Patent No.' 1,472,465 granted October 30, 1928, to Forsberg et al. together with anV additional two-winding relay 390 `are connected to provide the desired operation.

The stepping switch 380 is shown in the ready position and lincludes energizing windings 382 and two brushes or wipers 383, 384 connected to be progressively moved by the windings in clockwise stepsacross separate sets of stationary contacts 385, 386., A normally closed set of contacts 381 is also arranged to be opened each time the windings 382 are energized. Individual commutator contacts 388 are adjustably positioned to be engaged by the commutator segments 388, 389, and correspond in number to the vdesirednumber of .remotely controllable tuningY positions. The commutator contacts 388 are separately connected to Vthe. individual contacts of set 385. The first few contacts of the set 385 are left unconnected, while two contacts of the saine set are separately connected to the reversing windings 310, 312. All the contacts of set 386, except the one engaged by brush 384 in the ready position shown, are connected to a movable contact 393 of relay 390.

The stepping switch is also arranged to advance its arms 383, 384 only upon, the termination of an actuating pulse. vThus for example it may include a pawl and ratchet stepping mechanism connected so that the initiation of a pulse merely cocks the pawl against a bias spring while the cessation of the pulse permits the cocked pawl to advance the ratchet to the next step.

Relay 390 has a normal winding 39| and a slow release type of winding 382, both arranged to attract the movable switch contact 393 from its non-operated position against stationary contact 394 to an operated position against an opposed contact 395. The windings 39|, 392 as well as winding 382, 306, 381, 310 and 312 are all energized by suitable alternating or direct current power supplies, the oppositely polarized terminals of which are shown diagrammatically by the circled plus and minus signs.

As shown in Figure 4, the tuning motor 305 is at the fifth remotely controlled tuning position, the fifth (counting clockwise) of the group of contacts 385 being connected to the commutator brush 388 opposite a gap between commutator segments 388 and 389. To shift the tuning to the fourth position, a sequence of eight pulses of reflection changing are effected. Eight 'currentpulses are accordingly passed by the detector 326 through the windings of relay 30|.

At each pulse contacts 302 and 303 close momentarily. Closing of contacts 302 completes an energizing circuit for the stepping switch windings 382 through the slow release windings 392, advancing the arms 383, 384 one step. Contacts 303 in closing establish an energizing circuit for the volume control windings 310, 312. At every step away from the ready position, arm 384 connects one power supply terminal to movable contact 383 which throughout the pulsing is held in its operated position against contact 395 by the slow release characteristic of the winding 392. In this operated position contacts 393, 395 prepare an energizing circuit for windings 39| and tuning motor 305 through arm 383, commutator segment brushes 388, and one of the direction controlling windings 388, 381. The relay windings 39| act as a holding device to maintain this circuit energized so long as it is completed, regardless of the cessation of control pulses in relay 30 I.

contacts 381.

At the eighth pulse, arm'383 reaches the contact of set 385 connected to the fourth tuning brush 388. The tuning motor circuit is thereby closed through windings 306 causing the motor to turn the commutator segments in the clockwise direction as seen in Figure 4, until the gap between Ythe segmentsis moved to the fourth brush 388, opening the energizing circuit and stopping further tuning. y

Relay windings 39| thereupon become deenergized,` and if a suiiicient time has elapsed for slow release windings 392 to release, contact 393 returns to its non-operated position against contact 394 where it completes an energizing circuit for stepping switch windings 382 through These last contacts act as interruption contacts causingthe stepping switch to step itself along to the ready position shown where the arm 384 is no longer connected to contact 393 and further operation ceases.

On the way up to the fourth brush 388, arm 383 stops momentarily at the volume control windings 310, 312, as well as the rst, second and third tuning positions. Inasmuch as these pauses are of relativelyshort duration no signicant control operation is produced.

The above tuning operation also applies to the other tuning positions which only differ in the number of steps involved.

For increasing the signal output intensity or volume, three remote control pulses are effected,

- followed by a series of remote control vibrations of higher frequency. The three pulses bring the arm 383 to the contact 38'5 connected to winding 310 of the volume control motor, in the same manner as the tuning. At the completion of the third pulse the relay 30| would be deenergized were it not for the succeeding vibrations which keep it energized so that its sets of contacts 302, 303 remain closed. The volume control motor is accordingly energized through contacts 303 and windings 310 until the vibrations are completed, permitting the contacts 303 to return to open position. After the slow release windings 392 permit contact 393 to return to non-operated position against contact 394, the stepping switch steps itself back to the ready position.

The first few contacts of set 385 may be left disconnected to prevent undesired operation in response to electrical noise, static or other interfering waves.

Decreasing the volume is accomplished in the same manner, windings 312 being energized instead of windings 310. The volume controlmotor may also be arranged to automatically shut off the controlled radio receiver at the lower limit of volume, as `by, conventional limit switches.

It will be noted that the control operations described in connection with Figure 4 are readily effected with a remote control unit of the type shown in Figure 3. The various openings C to J. inclusive, may have associated legends identifying the corresponding tuning positions, openings A and B being marked, respectively, onvolume up and volume down-off.

A feature of the invention is that the volume control is readily eifected in a simple manner. It is only necessary to dial A or B, and after releasing the dial 25| to press the vibration control button 269 till the desired change in volume is reached, after which the button is released. The completion of the pulsing occupies some time after the dial is released and the slow release of windings392 permit more time to elapse before 9 the vibration is started, without interrupting the sequential control action.

The permissible manipulation time interval is increased readily if desired as by locating the volume control openings 252 at the I and J positions or at some positions between A and J.

The generator 3I4, amplifier 323' and detector 326 can be operated with electron discharge tubes that consume a minimum amount of power to limit the power drain of the control apparatus which may be continuously in operation. Vacuum tubes of the type having directly heated cathodes are suitable for this purpose. As pointed out above, the heterodyne circuit may function without a power supply, by using the well known crystal type mixers.

The generator 3|4 may have a vacuum tube oscillator modulated in frequency at a 60 or 120 cycle rate by a variable condenser vibrated directly by the commercially supplied alternating current power, so that the generator needs only one electron discharge device and uses very little power.

Although the remote control antennas have been shown as dipoles for use at very high radio frequencies, they can also be of other types such as loop antennas and thereby conveniently used with lower remote control frequencies, as low as 100 kilocycles per second, for example.

While several exempliications of the invention have been indicated and described above, it will be apparent to those skilled in the art that other modifications may be made without departing from the scope of the invention as set forth in the appended claim.

What is claimed is:

I n a remote control system the combination of a receiver to be controlled; a source of carrier oscillations, a delay network and a transmitting antenna connected in series in the order named; a powerless remote control unit including a reflective antenna, a plurality of individual antenna impedance changing circuits connected to said reiiective antenna, and means for actuating each of said circuits so as to change the impedance of said reflective antenna in accordance with a predetermined sequence whereby the energy reiiected from said reflective antenna varies in accordance with said sequence; antenna means adjacent said receiver for receiving said reflected waves; a sensing unit connected in series with said delay network and said antenna means to detect remote circuit changes, a selector unit energized by the output from said sensing unit; said selector unit having a plurality of output circuits; control units connected to said receiver and adapted to Vary the tuning and volume of said receiver; each of said control units being individually connected to one of said output circuits whereby the operation of said receiver is controlled in accordance with the received sequence.

ROBERT L. HARVEY.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,744,036 Brard Jan. 3l, 1930 2,045,071 Espenschied June 23, 1936 2,235,815 Perroux Mar. 25, 1941 2,297,618 Grimes et al Sept. 29, 1942 2,334,011 Kline Nov. 9, 1943 2,440,253 Dodington Apr. 27, 1948 2,461,646 Lewis Feb. 15, 1949 2,475,127 Carlson July 5, 1949 2,493,774 Moore Jan. 10, 1950 OTHER REFERENCES Lindenblad, Abstract of Application, Serial No. 695,509, published August 23, 1949. 

